For example, a technique described in Japanese examined patent publication No.2003-71776 has been known as a technique for a leg type mobile robot, particularly the structure of a foot of the leg type mobile robot. A foot of the leg type walking robot described in Patent Reference 1 is composed by a force sensor (floor reaction force detector) for detecting floor reaction force, a spring mechanism provided with a elastic member having an impact absorbing function, a foot sole frame, a foot sole plate and a sole sequentially from above.
The force sensor is connected to the foot sole frame via the spring mechanism, and shock added to the force sensor at the time of landing, particularly the shock acted in an oblique direction can be reduced by the deformation of the elastic member.
However, the leg type walking robot described in Japanese examined patent publication No. 2003-71776 requires a lager number of components and a complicated structure.
There is a desire to enhance the speed (walk and run) of the movement of the above leg type walking robot. When the leg type walking robot moves at a high speed, large inertia force is generated on the leg part. So as to reduce the inertia force, there is a desire to reduce the weight of the end side of the leg part, that is, the weight of a foot.
Since impulse force due to the floor reaction force added to the foot at the time of being grounded also becomes larger when the leg type walking robot moves at high speed, it is preferable that the foot of the leg type walking robot has a structure capable of enduring the impulse force.
Therefore, there have been required to provide a leg type mobile robot which can absorb the shock at the time of landing in spite of a simple structure and has the foot reduced in weight.